Construction method for continuous mining machine having device continuously providing provisional roof support

ABSTRACT

A method for operating a continuous mining machine having a device continuously providing provisional roof support, wherein the mining machine a rolling roof-protection portion which is fixed on a main machine frame of the continuous mining machine via a front column structure and a rear column structure. While the machine is cutting, the roof-protection device performs continuous load holding on a roof, and after cutting, performs support operations, thereby achieving simultaneous performance of cutting and support operations, and improving tunneling efficiency. Different support strengths are configured according to the hardness, completeness, and quality indicators of rock on a mine roof, such that the device is able to effectively support the roof.

TECHNICAL FIELD

The present invention relates to continuous mining machines,particularly to a construction method for a continuous mining machinewith a continuous temporary roof protection device.

BACKGROUND ART

Mining and driving are two crucial links in the coal mine productionsystem engineering. Bolt supporting is a supporting method widelyapplied in coal mine roadways in China owing to its advantages, such ashigh safety, high flexibility and high efficiency, etc. With thecontinuous improvement of mechanization, automation and intelligence,the efficiency of fully mechanized coal mining is gradually improved. Incontrast, owing to the influence of the present supporting techniques,the improvement of driving speed is very low, resulting in imbalancebetween mining and driving in coal production. Under the condition ofexisting bolt support techniques, it is of great significance to improvethe driving speed to mitigate the contradiction in mining and drivingsuccession and improve the overall production efficiency of the mines.

Boom-type roadheader with single roof bolter and continuous miningmachine with roof bolting jumbo are two most common tunneling supportingtechniques. Under the driving supporting condition of traditionalboom-type roadheader with single roof bolter, the roadheader has to bestopped and retreated after cutting to certain footage, so that thesingle roof bolter can enter the working face to carry out supportingoperation; under the driving condition of continuous mining machine withroof bolting jumbo, the continuous mining machine has to be withdrawn ormoved to another roadway after cutting to certain footage, so that theroof bolting jumbo can enter the working face to carry out supportingoperation. An important feature of the above-mentioned two supportingtechniques is that the bolt supporting operation is carried out in frontof the cutting equipment. Consequently the cutting operation and thebolt supporting operation can't be carried out in parallel. Thealternating execution of cutting operation and bolt supporting operationresults in a low operation rate of the equipment, and seriouslyrestricts the improvement of the overall driving efficiency. Carryingout effective temporary supporting for the roof after cutting andperforming bolt supporting behind of the cutting equipment are importantprerequisites for realizing parallel operation of cutting and supportingand thereby improving driving efficiency.

Contents of the Invention

The object of the present invention is to provide a construction methodfor a continuous mining machine with a continuous temporary roofprotection device, so as to solve the problem that the bolt supportingoperation and the cutting operation can't be carried out in parallelbecause the bolt supporting operation has to be carried out in front ofthe driving equipment and consequently the driving efficiency iscompromised.

In order to attain the technical object described above, the presentinvention employs the following technical solution:

A method construction for a continuous mining machine with a continuoustemporary roof protection device comprises a continuous mining machine,wherein the continuous mining machine comprises a main machine part, aloading device, a horizontal-shaft cutting drum, a conveying device anda crawler travel device, wherein the horizontal-shaft cutting drum ishinged to the front portion of the main machine part, the front portionof the conveying device is connected to the loading device and theconveying device is fixedly connected to the main machine part, and thecrawler travel device employs hydraulic driving and is fixed to thebottom of the main machine part, wherein the continuous mining machinefurther comprises a continuous temporary roof protection device, theloading device and the horizontal-shaft cutting drum are disposed infront of the continuous temporary roof protection device, and thecontinuous temporary roof protection device comprises a rolling roofprotection part fixed to the main machine part of the continuous miningmachine via a front pillar structure and a rear pillar structure;

the rolling roof protection part comprises a frame body, a closedcrawler track loop, a first roller, a second roller and elastic loadbearing structures, wherein the first roller and the second roller arerespectively hinged to two ends of the frame body, the closed crawlertrack loop is wound on the first roller and the second roller and is ina rolling connection with the first roller and the second roller, aplurality of guide sleeves are fixed inside the frame body, the guidesleeves are connected with the elastic load bearing structures, and theelastic load bearing structures are in a rolling connection with theclosed crawler track loop;the front pillar structure comprises a front square inner sleeve, afront square outer sleeve and a front height-adjusting oil cylinder,wherein the bottom of the front square outer sleeve is fixed to the mainmachine part of the continuous mining machine by bolts, the front squareinner sleeve is embedded in the front square outer sleeve, the bottom ofthe cylinder body of the front height-adjusting oil cylinder is hingedto the front square outer sleeve, a piston rod of the frontheight-adjusting oil cylinder is hinged to the front square innersleeve, and the top end of the front square inner sleeve is hinged tothe frame body; the rear pillar structure comprises a rear square innersleeve, a rear square outer sleeve and a rear height-adjusting oilcylinder, wherein the bottom of the rear square outer sleeve is fixed tothe main machine part of the continuous mining machine by bolts, therear square inner sleeve is embedded in the rear square outer sleeve,the bottom of the cylinder body of the rear height-adjusting oilcylinder is hinged to the rear square outer sleeve, a piston rod of therear height-adjusting oil cylinder is hinged to the rear square innersleeve, and a waist-shaped hole structure at the top end of the rearsquare inner sleeve is slidably and rotatably connected with the framebody via a pin shaft;an oil inlet bypass of a rodless cavity of the front height-adjustingoil cylinder and an oil inlet bypass of a rodless cavity of the rearheight-adjusting oil cylinder are connected with an accumulatorrespectively, two oil inlets of the front height-adjusting oil cylinderare connected with a reversing valve via a hydraulic lock, two oilinlets of the rear height-adjusting oil cylinder are connected with thereversing valve via another hydraulic lock, and a pressure gauge and anoverflow valve are provided between the reversing valve and thehydraulic locks;the horizontal-shaft cutting drum is adjustable in length and itsmaximum length is the same as the width WO of the roadway to beconstructed, and the total width of the loading device is smaller thanthe width WO of the roadway to be constructed; the construction methodcomprises the following steps:

-   -   a. classifying the roof strata of the roadway to be constructed        as per GB/T 50218-2014 “Standard for Classification of        Engineering Rock Masses” according to the geological conditions        of the region where the roadway is to be constructed, wherein        the continuous mining machine is suitable for constructing        roadways with Class I, Class II or Class III roof strata;    -   b. qualitatively classifying the stiffness and integrity of the        roof rock mass of the roadway to be constructed as per GB/T        50218-2014 “Standard for Classification of Engineering Rock        Masses”, and determining the supporting strength Pr of the        continuous temporary roof protection device according to the        result of qualitative classification and a quality index of the        rock mass;    -   c. calculating the pressure Pc on the front height-adjusting oil        cylinder and the rear height-adjusting oil cylinder with the        following formula, according to the supporting strength Pr        determined in the step b:

$\begin{matrix}{{P_{c} = \frac{P_{r} \times {WO} \times L}{4 \times 3.14 \times R^{2}}};} & (1)\end{matrix}$

-   -    wherein R is the cylinder diameter of the front        height-adjusting oil cylinder or the rear height-adjusting oil        cylinder, L is the length of contact surface between the rolling        roof protection part and the roof, and WO is the width of the        roadway to be constructed;    -   d. setting the pressure on the front height-adjusting oil        cylinder and the rear height-adjusting oil cylinder according to        the pressure result calculated in the step c, i.e., adjusting        the overflow pressure value of the overflow valve to the        pressure value calculated in the step c with the aid of the        pressure gauge;    -   e. manipulating the handle of the reversing valve to supply oil        to the accumulator, the front height-adjusting oil cylinder and        the rear height-adjusting oil cylinder while observing the        pressure indicated by the pressure gauge, and holding the        pressure for 3 s when the pressure indicated by the pressure        gauge can't increase anymore;    -   f determining the cutting footage of the continuous mining        machine according to the array pitch of the roof bolts in a        predefined scheme to set the distance of the cutting footage in        each cycle to be equal to the array pitch of the roof bolts in        the predefined scheme, operating the horizontal-shaft cutting        drum of the continuous mining machine to cut the coal according        to the distance of the cutting footage in each cycle, shoveling        the coal and rock cut by the horizontal-shaft cutting drum with        the loading device, and conveying the coal and rock with the        conveying device to the rear part and then conveying the coal        and rock away;    -   g. advancing the continuous mining machine forward by a distance        corresponding to the cutting footage by means of the crawler        travel device after the coal cutting, while the rolling roof        protection part of the continuous temporary roof protection        device persistently supports the roof of the constructed        roadway;    -   h. operating the continuous mining machine to carry out the next        cycle of coal cutting after the advancing, while the workers use        a roof bolter to support the roof with rock bolts behind the        continuous mining machine;    -   i. executing the step b again after cutting to a preset        distance, i.e., determining the supporting strength Pr of the        continuous temporary roof protection device again according to        the conditions of the roof rock mass of the roadway to be        constructed, and operating the continuous mining machine to do        the construction work forward in a preset roadway direction,        till the roadway driving work is completed.

As a further improved technical solution of the present invention, thetotal width of the loading device is smaller than the width WO of theroadway to be constructed by 200 mm.

As a further improved technical solution of the present invention, thestep b comprises: qualitatively classifying the stiffness and integrityof the roof rock mass of the roadway to be constructed as per GB/T50218-2014 “Standard for Classification of Engineering Rock Masses”;

determining the supporting strength Pr of the continuous temporary roofprotection device to be Pr=0.02 MPa, if the result of qualitativeclassification of the stiffness and integrity of the roof rock mass ofthe roadway indicates that the rock is stiff rock and the rock mass isintegral, and the quality index BQ of the rock mass is BQ>550;determining the supporting strength Pr of the continuous temporary roofprotection device to be Pr=0.05 MPa, if the result of qualitativeclassification of the stiffness and integrity of the roof rock mass ofthe roadway indicates that the rock is stiff and the rock mass isgenerally integral, or the rock is generally stiff and the rock mass isintegral, and the quality index BQ of the rock mass is 451 to 550;determining the supporting strength Pr of the continuous temporary roofprotection device to be Pr=0.1 MPa, if the result of qualitativeclassification of the stiffness and integrity of the roof rock mass ofthe roadway indicates that the rock is stiff and the rock mass isgenerally fractured, or the rock is generally stiff and the rock mass isgenerally integral, or the rock is generally soft and the rock mass isintegral, and the quality index BQ of the rock mass is 351 to 450. As afurther improved technical solution of the present invention, the presetdistance in the step i is 50 m.

As a further improved technical solution of the present invention, theelastic load bearing structure comprises a load bearing roller, a forkframe and a butterfly spring set, wherein the load bearing roller is ina rolling connection with the closed crawler track loop and is hinged tothe fork frame, a limiting sleeve is provided at the lower part of thefork frame, a central cylinder is provided at the central part of thelimiting sleeve, the limiting sleeve of the fork frame is sleevedoutside the guide sleeve and the fork frame is in contact with thebutterfly spring set, the central cylinder of the fork frame is insertedinto a central hole of the butterfly spring set and the butterfly springset is placed inside the guide sleeve, and the closed crawler track loopis the component in contact with the roof of the roadway.

As a further improved technical solution of the present invention, theclosed crawler track loop is formed by a plurality of crawler trackshinged together, each of which comprises a track shoe substrate, hardrubber and a chain track, wherein the hard rubber is fixed on the trackshoe substrate, the chain track is connected with the track shoesubstrate, and adjacent crawler tracks are hinged with each other viathe chain track.

As a further improved technical solution of the present invention, thehard rubber is bonded to the track shoe substrate by means of epoxyresin and fixed to the track shoe substrate by hex screws.

As a further improved technical solution of the present invention, therolling roof protection part comprises a tensioning mechanism, which isconfigured to push the first roller so as to tension up the closedcrawler track loop.

As a further improved technical solution of the present invention, twocontinuous temporary roof protection devices are provided.

The present invention attains the following beneficial effects:

-   (1) With the construction method provided by the present invention,    the continuous temporary roof protection device can persistently    protect and support the roof while the continuous mining machine is    cutting. Therefore, it is unnecessary to stop and retreat the    continuous mining machine to enable the roof bolter to reach to the    front. The continuous temporary roof protection device can    effectively support the roof temporarily after the cutting, and the    bolt supporting operation is carried out behind the cutting    equipment. Thus, parallel operation of cutting and supporting is    realized, and the driving efficiency is improved. In the    construction method used in the present invention, different    supporting strengths are set according to the stiffness, integrity    and quality index of the roof rock mass, so that the continuous    temporary roof protection device can effectively support the roof,    and the problem that the bolt supporting operation of the roof    bolter can't be carried out effectively owing to inadequate    supporting strength is prevented.-   (2) With the construction method provided by the present invention,    the rolling roof protection part can persistently support the    exposed roof after the continuous mining machine carries out the    cutting operation, thus roof damages caused by repeated loading and    unloading of the roof during the displacement of the continuous    mining machine can be prevented; since the bolt supporting operation    can be carried out behind the continuous mining machine, it is    possible to realize parallel operation of cutting and supporting;    thus the driving efficiency is improved and the impact of bolt    supporting on the cutting operation is reduced.-   (3) The closed crawler track loop in the present invention is in    rolling contact with the elastic load bearing structures, the first    roller and the second roller. In the case that the roadway roof is    not flat, the butterfly spring sets of the elastic load bearing    structures have different compression amounts, so that the closed    crawler track loop is in good contact with the non-flat roadway    roof, achieving large area of contact with the roadway roof and high    safety.-   (4) In the present invention, pressure oil can be supplied to the    rodless cavity of the front height-adjusting oil cylinder and the    rodless cavity of the rear height-adjusting oil cylinder via the    reversing valve, the front height-adjusting oil cylinder and the    rear height-adjusting oil cylinder drive the rolling roof protection    part to bear the roof; when the reversing valve doesn't introduce    pressure oil into the front height-adjusting oil cylinder and the    rear height-adjusting oil cylinder, the pressure oil in the    accumulator maintains the front height-adjusting oil cylinder and    rear height-adjusting oil cylinder in a loaded state, thus    persistent load protection for the roof is ensured with the rolling    roof protection part, the efficiency is improved, and the labor    intensity is deceased.

DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of the continuous mining machine in the presentinvention in a working state in roadway driving;

FIG. 2 is a top view of the continuous mining machine in the presentinvention;

FIG. 3 is an oblique view of the continuous mining machine in thepresent invention;

FIG. 4 is a schematic structural diagram of the continuous temporaryroof protection device in the present invention;

FIG. 5 is a schematic structural diagram of the rolling roof protectionpart in the present invention;

FIG. 6 is a partial sectional view of the rolling roof protection partin the present invention;

FIG. 7 is a schematic structural diagram of the fork frame in thepresent invention;

FIG. 8 is a schematic structural diagram of the crawler track in thepresent invention;

FIG. 9 is a schematic structural diagram of the front pillar structurein the present invention;

FIG. 10 is a schematic structural diagram of the rear pillar structurein the present invention;

FIG. 11 is a schematic diagram of the hydraulic principle in the presentinvention.

EMBODIMENTS

Hereunder a specific embodiment of the present invention will be furtherdescribed with reference to FIGS. 1-11.

The embodiment is intended to provide a construction method for acontinuous mining machine with a continuous temporary roof protectiondevice, so as to solve the problem that the bolt supporting operationand the cutting operation can't be carried out in parallel because thebolt supporting operation has to be carried out in front of the drivingequipment and consequently the driving efficiency is compromised.Specifically: Please see FIG. 1. The reference numbers in FIG. 1 are asfollows: 1—roadway floor, 2—driving face, 3—unsupported roadway roofafter cutting, 4—supported roadway roof, 5—roof bolt, 6—continuousmining machine.

A construction method for a continuous mining machine 6 with acontinuous temporary roof protection device is provided, comprising acontinuous mining machine 6. FIG. 2 is a top view of the continuousmining machine 6. As shown in FIGS. 2 and 3, the continuous miningmachine 6 comprises a main machine part, a loading device 61, ahorizontal-shaft cutting drum 62, a conveying device 63 and a crawlertravel device 64; the horizontal-shaft cutting drum 62 is hinged to thefront portion of the main frame of the main machine part, the frontportion of the conveying device 63 is connected to the loading device 61and the conveying device 63 is fixedly connected to the main frame ofthe main machine part, and the crawler travel device 64 employshydraulic driving and is fixed to the bottom of the main machine part;the main machine part comprises a main frame, a hydraulic system, and anelectric control system, etc., wherein the hydraulic system and theelectric control system are fixed on the main frame and configured todrive the continuous mining machine to work. All of the specificstructures employ the driving structures of existing continuous miningmachines. The continuous mining machine 6 further comprises a continuoustemporary roof protection device, the loading device 61 and thehorizontal-shaft cutting drum 62 are disposed in front of the continuoustemporary roof protection device, and the continuous temporary roofprotection device comprises a rolling roof protection part A fixed tothe main frame of the main machine part of the continuous mining machine6 via a front pillar structure B and a rear pillar structure C; when thehorizontal-shaft cutting drum 62 carries out cutting operation, thecontinuous temporary roof protection device can persistently protect andsupport the roof so as to realize effective temporary supporting for theexposed roof after the cutting; the bolt supporting operation is carriedout behind the cutting equipment, so that it is unnecessary to stop orretreat the tunneling equipment to enable the roof bolter to reach tothe front; thus, parallel operation of cutting and supporting isrealized, and the driving efficiency is further improved.

As shown in FIGS. 4 and 5, the rolling roof protection part A comprisesa frame body A2, a closed crawler track loop A3, a first roller A10, asecond roller A1, and an elastic load bearing structures, wherein thefirst roller A10 and the second roller A1 are respectively hinged to twoends of the frame body A2 and can rotate with respect to the frame bodyA2; the closed crawler track loop A3 is wound on the first roller A10and the second roller A1, and is in a rolling connection with the firstroller A10 and the second roller A1; as shown in FIG. 6, a plurality ofguide sleeves A8 are fixed inside the frame body A2 (the frame body A2includes an elongated hollow shell and triangle-like brackets forconnecting with the front pillar structure B and the rear pillarstructure C, the left end and the right end of the elongated hollowshell are hinged with the first roller A10 and the second roller A1respectively, the top of the elongated hollow shell is open, the guidesleeves A8 are fixed on the inner bottom of the elongated hollow shell,and the triangle-like brackets are fixed on the front side wall and rearside wall of the elongated hollow shell for connecting with the frontpillar structure B and the rear pillar structure C; the specificstructure is shown in FIG. 4); the guide sleeves A8 are connected withthe elastic load bearing structures, and the elastic load bearingstructures are in a rolling connection with the closed crawler trackloop A3; that is to say, the closed crawler track loop A3 is in rollingcontact with the elastic load bearing structures, the first roller A10and the second roller A1. The first roller A10 and the second roller A1of the rolling roof protection part A can rotate freely; when thecontinuous mining machine is displaced forward or backward, the closedcrawler track loop A3 rolls along the roof in a loaded state, thuscontinuous temporary supporting for the roof is realized.

As shown in FIG. 9, the front pillar structure B comprises a frontsquare inner sleeve B1, a front square outer sleeve B2 and a frontheight-adjusting oil cylinder B3, wherein the bottom of the front squareouter sleeve B2 is fixed to the main frame of the main machine part ofthe continuous mining machine 6 by bolts; one end of the front squareinner sleeve B1 is embedded in the front square outer sleeve B2 and thefront square inner sleeve B1 can slide inside the front square outersleeve B2; the bottom of the cylinder body of the front height-adjustingoil cylinder B3 is hinged to the front square outer sleeve B2 via a pinshaft, the top of the cylinder body of the front height-adjusting oilcylinder B3 extends into the front square inner sleeve B1, the pistonrod of the front height-adjusting oil cylinder B3 is hinged to the frontsquare inner sleeve B1 via a pin shaft, and the top end of the frontsquare inner sleeve B1 is hinged to the frame body A2 via a pin shaft;the form of hinging is shown in FIG. 4; the front height-adjusting oilcylinder B3 is a double-acting oil cylinder, the rodless cavity of thelower oil port of the front height-adjusting oil cylinder B3 extends outof the bottom of the front square outer sleeve B1 through a pipeline andis connected with pressure oil, and the rod cavity of the upper oil portof the front height-adjusting oil cylinder B3 extends out of the bottomof the front square inner sleeve B2 and the bottom of the front squareouter sleeve B1 sequentially through a pipeline and is connected withpressure oil.

As shown in FIG. 10, the rear pillar structure C comprises a rear squareinner sleeve C1, a rear square outer sleeve C2 and a rearheight-adjusting oil cylinder C3, wherein the bottom of the rear squareouter sleeve C2 is fixed to the main frame of the main machine part ofthe continuous mining machine 6 by bolts; one end of the rear squareinner sleeve C1 is embedded in the rear square outer sleeve C2 and therear square inner sleeve C1 can slide inside the rear square outersleeve C2; the bottom of the cylinder body of the rear height-adjustingoil cylinder C3 is hinged to the rear square outer sleeve C2 via a pinshaft, the top of the cylinder body of the rear height-adjusting oilcylinder C3 extends into the rear square inner sleeve C1 and the pistonrod of the rear height-adjusting oil cylinder C3 is hinged to the rearsquare inner sleeve C1 via a pin shaft, and a waist-shaped holestructure C11 at the top end of the rear square inner sleeve C1 isconnected to the frame body A2 via a pin shaft in a slidable androtatable manner; the rear height-adjusting oil cylinder C3 is adouble-acting oil cylinder, and the waist-shaped hole structure C11provides a certain reserved space for absorbing the deviation. Thus, inthe case that the roof is not flat in the front-rear direction, therolling roof protection part A can tilt to an angle in the front-reardirection, without damaging the front and rear pillar structures.

As shown in FIG. 11, an oil inlet bypass of a rodless cavity of thefront height-adjusting oil cylinder B3 and an oil inlet bypass of arodless cavity of the rear height-adjusting oil cylinder C3 areconnected with an accumulator B6 respectively, two oil inlets of thefront height-adjusting oil cylinder B3 are connected with a reversingvalve B4 via a hydraulic lock B5, two oil inlets of the rearheight-adjusting oil cylinder C3 are connected with the reversing valveB4 via another hydraulic lock B5; pressure oil can be supplied to therodless cavity or rod cavity of the front height-adjusting oil cylinderB3 as well as the rodless cavity or rod cavity of the rearheight-adjusting oil cylinder C3 via the reversing valve B4, so as torealize the loading or unloading of the front height-adjusting oilcylinder B3 and the rear height-adjusting oil cylinder C3; when thereversing valve B4 does not supply pressure oil to the frontheight-adjusting oil cylinder B3 and the rear height-adjusting oilcylinder C3, the pressure oil in the accumulator B6 maintains the frontheight-adjusting oil cylinder B3 and the rear height-adjusting oilcylinder C3 in a loaded state, thus persistent load protection of theroof is ensured with the rolling roof protection part A. A pressuregauge B7 and an overflow valve B8 are arranged between the reversingvalve B4 and the hydraulic locks B5. The overflow pressure of theoverflow valve B8 may be adjusted with the aid of the pressure gauge B7to achieve different supporting strengths.

In this embodiment, two continuous temporary roof protection devices areprovided. Therefore, there are two front height-adjusting oil cylindersB3 and two rear height-adjusting oil cylinders C3.

The horizontal-shaft cutting drum 62 is adjustable in length and itsmaximum length is the same as the width WO of the roadway to beconstructed, and the total width of the loading device 61 is smallerthan the width WO of the roadway to be constructed by 200 mm.

The construction method comprises the following steps:

-   a. classifying the roof strata of the roadway to be constructed as    per GB/T 50218-2014 “Standard for Classification of Engineering Rock    Masses” according to the geological conditions of the region where    the roadway is to be constructed, wherein the continuous mining    machine 6 is suitable for constructing roadways with Class I, Class    II or Class III roof strata;-   b. qualitatively classifying the stiffness and integrity of the roof    rock mass of the roadway to be constructed as per GB/T 50218-2014    “Standard for Classification of Engineering Rock Masses”, and    determining the supporting strength Pr of the continuous temporary    roof protection device according to the result of qualitative    classification and a quality index of the rock mass;-   c. calculating the pressure Pc on the front height-adjusting oil    cylinder B3 and the rear height-adjusting oil cylinder C3 with the    following formula (1), according to the supporting strength Pr    determined in the step b:

$\begin{matrix}{{P_{c} = \frac{P_{r} \times {WO} \times L}{4 \times 3.14 \times R^{2}}};} & (1)\end{matrix}$

-   -   wherein R is the cylinder diameter of the front height-adjusting        oil cylinder B3 or the rear height-adjusting oil cylinder C3, L        is the length of contact surface between the rolling roof        protection part A and the roof, and WO is the width of the        roadway to be constructed;

-   d. setting the pressure on the front height-adjusting oil cylinder    B3 and the rear height-adjusting oil cylinder C3 according to the    pressure result calculated in the step c, i.e., adjusting the    overflow pressure value of the overflow valve B8 to the pressure    value calculated in the step c with the aid of the pressure gauge    B7;

-   e. manipulating the handle of the reversing valve B4 to supply oil    to the accumulator B6, the front height-adjusting oil cylinder B3    and the rear height-adjusting oil cylinder C3 while observing the    pressure indicated by the pressure gauge B7, and holding the    pressure for 3 s when the pressure indicated by the pressure gauge    B7 can't increase anymore;

-   f. determining the cutting footage of the continuous mining machine    6 according to the array pitch of the roof bolts in a predefined    scheme to set the distance of the cutting footage in each cycle to    be equal to the array pitch of the roof bolts in the predefined    scheme, operating the horizontal-shaft cutting drum 62 of the    continuous mining machine 6 to cut the coal according to the    distance of the cutting footage in each cycle, shoveling the coal    and rock cut by the horizontal-shaft cutting drum 62 with the    loading device 61, and conveying the coal and rock with the    conveying device 63 to the rear part and then conveying the coal and    rock away;

-   g. advancing the continuous mining machine 6 forward by a distance    corresponding to the distance of the cutting footage by means of the    crawler travel device 64 after the coal cutting, while the rolling    roof protection part A of the continuous temporary roof protection    device persistently supports the roof of the constructed roadway;

-   h. operating the continuous mining machine 6 to carry out the next    cycle of coal cutting after the advancing, while the workers use a    roof bolter to support the roof with rock bolts behind the    continuous mining machine 6; thus, simultaneous operation of coal    cutting and supporting is realized, and the roadway driving speed is    greatly improved;

-   i. executing the step b again after cutting to a preset distance,    i.e., determining the supporting strength Pr of the continuous    temporary roof protection device again according to the conditions    of the roof rock mass of the roadway to be constructed, and    operating the continuous mining machine 6 to do the construction    work forward in a preset roadway direction, till the roadway driving    work is completed. In the step i, the preset distance is 50 m.

In this embodiment, the step b comprises:

-   (1) qualitatively classifying the stiffness and integrity of the    roof rock mass of the roadway to be constructed as per GB/T    50218-2014 “Standard for Classification of Engineering Rock Masses”;-   (2) determining the supporting strength Pr of the continuous    temporary roof protection device to be Pr=0.02 MPa, if the result of    qualitative classification of the stiffness and integrity of the    roof rock mass of the roadway indicates that the rock is stiff rock    and the rock mass is integral, and the quality index BQ of the rock    mass is BQ>550; determining the supporting strength Pr of the    continuous temporary roof protection device to be Pr=0.05 MPa, if    the result of qualitative classification of the stiffness and    integrity of the roof rock mass of the roadway indicates that the    rock is stiff and the rock mass is generally integral, or the rock    is generally stiff and the rock mass is integral, and the quality    index BQ of the rock mass is 451 to 550; determining the supporting    strength Pr of the continuous temporary roof protection device to be    Pr=0.1 MPa, if the result of qualitative classification of the    stiffness and integrity of the roof rock mass of the roadway    indicates that the rock is stiff and the rock mass is generally    fractured, or the rock is generally stiff and the rock mass is    generally integral, or the rock is generally soft and the rock mass    is integral, and the quality index BQ of the rock mass is 351 to    450.

In this embodiment, the continuous mining machine 6 is provided with acontinuous temporary roof protection device, which can persistentlyprotect and support the roof while the continuous mining machine carriesout the cutting operation. Therefore, it is unnecessary to stop andretreat the continuous mining machine 6 to enable the roof bolter toreach to its front. The continuous temporary roof protection device caneffectively support the roof temporarily after the cutting operation,and the bolt supporting operation is carried out behind the cuttingequipment. All of those features are important prerequisites forrealizing parallel operation of cutting and supporting and therebyfurther improving the driving efficiency. In the construction methodused in this embodiment, different supporting strengths are setaccording to the stiffness, integrity and quality index of the roof rockmass, so that the continuous temporary roof protection device caneffectively support the roof, and the problem that the bolt supportingoperation of the roof bolter can't be carried out effectively owing toinadequate supporting strength is prevented.

In this embodiment, as shown in FIG. 6, the elastic load bearingstructure comprises a load bearing roller A6, a fork frame A5 and abutterfly spring set A7, wherein the load bearing roller A6 is in arolling connection with the closed crawler track loop A3 through the topof an elongated hollow shell of the frame body A2 and is hinged to thefork frame A5, and can rotate freely; as shown in FIG. 7, a limitingsleeve A11 is provided at the lower part of the fork frame A5, a centralcylinder A12 is provided at the central part of the limiting sleeve A11,the limiting sleeve A11 of the fork frame A5 is sleeved outside theguide sleeve A8 and the fork frame A5 is in contact with the butterflyspring set A7, the central cylinder A12 of the fork frame A5 is insertedinto a central hole of the butterfly spring set A7 and the butterflyspring set A7 is placed inside the guide sleeve A8, and the closedcrawler track loop A3 is the component in contact with the roof of theroadway. The closed crawler track loop A3 is in rolling contact with theelastic load bearing structures, the first roller A10 and the secondroller A1. In the case that the roadway roof is not flat, the butterflyspring sets A7 of the plurality of elastic load bearing structures havedifferent compression amounts, thereby the closed crawler track loop A3can be in good contact with the non-flat roadway roof.

In this embodiment, the closed crawler track loop A3 is formed by aplurality of crawler tracks A4 hinged together, as shown in FIG. 8, eachof which comprises a track shoe substrate A13, hard rubber A14 and achain track A16, wherein the hard rubber A14 is fixed on the track shoesubstrate A13, the chain track A16 is connected with the track shoesubstrate A13, and adjacent crawler tracks A4 are hinged with each othervia the chain track A16.

In this embodiment, as shown in FIG. 8, the hard rubber A14 is bonded tothe track shoe substrate A13 by means of epoxy resin and fixed to thetrack shoe substrate A13 by hex screws A15.

In this embodiment, as shown in FIG. 6, the rolling roof protection partA comprises a tensioning mechanism A9, which may be a tensioner commonlyused in the prior art, the tensioning mechanism A9 is arranged in theelongated hollow shell of the frame body A2 and configured to push thefirst roller A10 so as to tension up the closed crawler track loop A3.The first roller A10 is connected to an end of the frame body A2 in a360-degree rotatable manner, and the first roller A10 is connected withan end of the frame body A2 in a horizontally slidable manner and has acertain horizontal sliding space, thus providing a tensioning stroke forthe tensioning mechanism A9.

In the operation of this embodiment, firstly, the front height-adjustingoil cylinder B3 drives the front square inner sleeve B1 under the actionof pressure oil, the front square inner sleeve B1 pushes the frame bodyA2 in the rolling roof protection part A, and the front square innersleeve B1 is hinged to the frame body A2; the rear height-adjusting oilcylinder C3 drives the rear square inner sleeve C1 under the action ofpressure oil, the rear square inner sleeve C1 pushes the frame body A2in the rolling roof protection part A, and the rear square inner sleeveC1 is connected with the frame body A2 in a horizontally slidable androtatable manner. The first roller A10 and the second roller A1 hingedto the frame body A2 drive the closed crawler track loop A3 to rollalong the roadway roof, as a result of the travel of the continuousmining machine 6; the closed crawler track loop A3 is in rolling contactwith the elastic load bearing structures, the first roller A10 and thesecond roller A1; the butterfly spring sets A7 of the multiple elasticload bearing structures have different compression amounts, so that theclosed crawler track loop A3 is in good contact with the non-flatroadway roof; finally, temporary supporting for the roadway roof isrealized.

1-9. (canceled)
 10. A method for operating a continuous mining machinewith a continuous temporary roof protection device wherein thecontinuous mining machine comprises a main machine part, a loadingdevice, a horizontal-shaft cutting drum, a conveying device and acrawler travel device, wherein the horizontal-shaft cutting drum ishinged to the front portion of the main machine part, the front portionof the conveying device is connected to the loading device and theconveying device is fixedly connected to the main machine part, and thecrawler travel device employs hydraulic driving and is fixed to thebottom of the main machine part, wherein the continuous mining machinefurther comprises a continuous temporary roof protection device, theloading device and the horizontal-shaft cutting drum are disposed infront of the continuous temporary roof protection device, and thecontinuous temporary roof protection device comprises a rolling roofprotection part fixed to the main machine part of the continuous miningmachine via a front pillar structure and a rear pillar structure; therolling roof protection part comprises a frame body, a closed crawlertrack loop, a first roller, a second roller and an elastic load bearingstructures, wherein the first roller and the second roller arerespectively hinged to two ends of the frame body, the closed crawlertrack loop is wound on the first roller and the second roller and is ina rolling connection with the first roller and the second roller, aplurality of guide sleeves are fixed inside the frame body, the guidesleeves are connected with the elastic load bearing structures, and theelastic load bearing structures are in a rolling connection with theclosed crawler track loop; the front pillar structure comprises a frontsquare inner sleeve, a front square outer sleeve and a frontheight-adjusting oil cylinder, wherein the bottom of the front squareouter sleeve is fixed to the main machine part of the continuous miningmachine by bolts, the front square inner sleeve is embedded in the frontsquare outer sleeve, the bottom of the cylinder body of the frontheight-adjusting oil cylinder is hinged to the front square outersleeve, a piston rod of the front height-adjusting oil cylinder ishinged to the front square inner sleeve, and the top end of the frontsquare inner sleeve is hinged to the frame body; the rear pillarstructure comprises a rear square inner sleeve, a rear square outersleeve and a rear height-adjusting oil cylinder, wherein the bottom ofthe rear square outer sleeve is fixed to the main machine part of thecontinuous mining machine by bolts, the rear square inner sleeve isembedded in the rear square outer sleeve, the bottom of the cylinderbody of the rear height-adjusting oil cylinder is hinged to the rearsquare outer sleeve, a piston rod of the rear height-adjusting oilcylinder is hinged to the rear square inner sleeve, and a waist-shapedhole structure at the top end of the rear square inner sleeve isslidably and rotatably connected with the frame body via a pin shaft; anoil inlet bypass of a rodless cavity of the front height-adjusting oilcylinder and an oil inlet bypass of a rodless cavity of the rearheight-adjusting oil cylinder are connected with an accumulatorrespectively, two oil inlets of the front height-adjusting oil cylinderare connected with a reversing valve via a hydraulic lock, two oilinlets of the rear height-adjusting oil cylinder are connected with thereversing valve via another hydraulic lock, and a pressure gauge and anoverflow valve are provided between the reversing valve and thehydraulic locks; the horizontal-shaft cutting drum is adjustable inlength and its maximum length is the same as the width WO of the roadwayto be constructed, and the total width of the loading device is smallerthan the width WO of the roadway to be constructed; the constructionmethod comprises the following steps: a. classifying the roof strata ofthe roadway to be constructed as per GB/T 50218-2014 “Standard forClassification of Engineering Rock Masses” according to the geologicalconditions of the region where the roadway is to be constructed, whereinthe continuous mining machine is suitable for constructing roadways withClass I, Class II or Class III roof strata; b. qualitatively classifyingthe stiffness and integrity of the roof rock mass of the roadway to beconstructed as per GB/T 50218-2014 “Standard for Classification ofEngineering Rock Masses”, and determining the supporting strength Pr ofthe continuous temporary roof protection device according to the resultof qualitative classification and a quality index of the rock mass; c.calculating the pressure Pc on the front height-adjusting oil cylinderand the rear height-adjusting oil cylinder with the following formula,according to the supporting strength Pr determined in the step b:$\begin{matrix}{{P_{c} = \frac{P_{r} \times {WO} \times L}{4 \times 3.14 \times R^{2}}};} & (1)\end{matrix}$ wherein R is the cylinder diameter of the frontheight-adjusting oil cylinder or the rear height-adjusting oil cylinder,L is the length of contact surface between the rolling roof protectionpart and the roof, and WO is the width of the roadway to be constructed;d. setting the pressure on the front height-adjusting oil cylinder andthe rear height-adjusting oil cylinder according to the pressure resultcalculated in the step c, i.e., adjusting the overflow pressure value ofthe overflow valve to the pressure value calculated in the step c withthe aid of the pressure gauge; e. manipulating the handle of thereversing valve to supply oil to the accumulator, the frontheight-adjusting oil cylinder and the rear height-adjusting oil cylinderwhile observing the pressure indicated by the pressure gauge, andholding the pressure for 3 s when the pressure indicated by the pressuregauge fails to increase anymore; f. determining the cutting footage ofthe continuous mining machine according to the array pitch of the roofbolts in a predefined scheme to set the distance of the cutting footagein each cycle to be equal to the array pitch of the roof bolts in thepredefined scheme, operating the horizontal-shaft cutting drum of thecontinuous mining machine to cut the coal according to the distance ofthe cutting footage in each cycle, shoveling the coal and rock cut bythe horizontal-shaft cutting drum with the loading device, and conveyingthe coal and rock with the conveying device to the rear part and thenconveying the coal and rock away; g. advancing the continuous miningmachine forward by a distance corresponding to the cutting footage bymeans of the crawler travel device after the coal cutting, while therolling roof protection part of the continuous temporary roof protectiondevice persistently supports the roof of the constructed roadway; h.operating the continuous mining machine to carry out the next cycle ofcoal cutting after the advancing, while workers use a roof bolter tosupport the roof with rock bolts behind the continuous mining machine;i. executing the step b again after cutting to a preset distance,determining the supporting strength Pr of the continuous temporary roofprotection device again according to the conditions of the roof rockmass of the roadway to be constructed, and operating the continuousmining machine to do the construction work forward in a preset roadwaydirection, till the roadway driving work is completed.
 11. The methodaccording to claim 10, wherein the total width of the loading device issmaller than the width WO of the roadway to be constructed by 200 mm.12. The method according to claim 11, wherein the step b comprises: (1)qualitatively classifying the stiffness and integrity of the roof rockmass of the roadway to be constructed as per GB/T 50218-2014 “Standardfor Classification of Engineering Rock Masses”; (2) determining thesupporting strength Pr of the continuous temporary roof protectiondevice to be Pr=0.02 MPa, if the result of qualitative classification ofthe stiffness and integrity of the roof rock mass of the roadwayindicates that the rock is stiff rock and the rock mass is integral, andthe quality index BQ of the rock mass is BQ>550; determining thesupporting strength Pr of the continuous temporary roof protectiondevice to be Pr=0.05 MPa, if the result of qualitative classification ofthe stiffness and integrity of the roof rock mass of the roadwayindicates that the rock is stiff and the rock mass is generallyintegral, or the rock is generally stiff and the rock mass is integral,and the quality index BQ of the rock mass is 451 to 550; determining thesupporting strength Pr of the continuous temporary roof protectiondevice to be Pr=0.1 MPa, if the result of qualitative classification ofthe stiffness and integrity of the roof rock mass of the roadwayindicates that the rock is stiff and the rock mass is generallyfractured, or the rock is generally stiff and the rock mass is generallyintegral, or the rock is generally soft and the rock mass is integral,and the quality index BQ of the rock mass is 351 to
 450. 13. The methodaccording to claim 10, wherein in the step i, the preset distance is 50m.
 14. The method according to claim 10, wherein the elastic loadbearing structure comprises a load bearing roller, a fork frame and abutterfly spring set, wherein the load bearing roller is in a rollingconnection with the closed crawler track loop and is hinged to the forkframe, a limiting sleeve is provided at the lower part of the forkframe, a central cylinder is provided at the central part of thelimiting sleeve, the limiting sleeve of the fork frame is sleevedoutside the guide sleeve and the fork frame is in contact with thebutterfly spring set, the central cylinder of the fork frame is insertedinto a central hole of the butterfly spring set and the butterfly springset is placed inside the guide sleeve, and the closed crawler track loopis the component in contact with the roof of the roadway.
 15. The methodaccording to claim 10, wherein the closed crawler track loop is formedby a plurality of crawler tracks hinged together, each of whichcomprises a track shoe substrate, hard rubber and a chain track, whereinthe hard rubber is fixed on the track shoe substrate, the chain track isconnected with the track shoe substrate, and adjacent crawler tracks arehinged with each other via the chain track.
 16. The method according toclaim 15, wherein the hard rubber is bonded to the track shoe substrateby epoxy resin and fixed to the track shoe substrate by hex screws. 17.The method according to claim 10, wherein the rolling roof protectionpart comprises a tensioning mechanism, which is configured to push thefirst roller to tension up the closed crawler track loop.
 18. The methodaccording to claim 10, wherein two continuous temporary roof protectiondevices are provided.
 19. The method according to claim 11, wherein inthe step i, the preset distance is 50 m.
 20. The method according toclaim 11, wherein the elastic load bearing structure comprises a loadbearing roller, a fork frame and a butterfly spring set, wherein theload bearing roller is in a rolling connection with the closed crawlertrack loop and is hinged to the fork frame, a limiting sleeve isprovided at the lower part of the fork frame, a central cylinder isprovided at the central part of the limiting sleeve, the limiting sleeveof the fork frame is sleeved outside the guide sleeve and the fork frameis in contact with the butterfly spring set, the central cylinder of thefork frame is inserted into a central hole of the butterfly spring setand the butterfly spring set is placed inside the guide sleeve, and theclosed crawler track loop is the component in contact with the roof ofthe roadway.
 21. The method according to claim 11, wherein the closedcrawler track loop is formed by a plurality of crawler tracks hingedtogether, each of which comprises a track shoe substrate, hard rubberand a chain track, wherein the hard rubber is fixed on the track shoesubstrate, the chain track is connected with the track shoe substrate,and adjacent crawler tracks are hinged with each other via the chaintrack.
 22. The method according to claim 21, wherein the hard rubber isbonded to the track shoe substrate by epoxy resin and fixed to the trackshoe substrate by hex screws.
 23. The method according to claim 11,wherein the rolling roof protection part comprises a tensioningmechanism, which is configured to push the first roller to tension upthe closed crawler track loop.
 24. The method according to claim 11,wherein two continuous temporary roof protection devices are provided.25. The method according to claim 12, wherein in the step i, the presetdistance is 50 m.
 26. The method according to claim 12, wherein theelastic load bearing structure comprises a load bearing roller, a forkframe and a butterfly spring set, wherein the load bearing roller is ina rolling connection with the closed crawler track loop and is hinged tothe fork frame, a limiting sleeve is provided at the lower part of thefork frame, a central cylinder is provided at the central part of thelimiting sleeve, the limiting sleeve of the fork frame is sleevedoutside the guide sleeve and the fork frame is in contact with thebutterfly spring set, the central cylinder of the fork frame is insertedinto a central hole of the butterfly spring set and the butterfly springset is placed inside the guide sleeve, and the closed crawler track loopis the component in contact with the roof of the roadway.
 27. The methodaccording to claim 12, wherein the closed crawler track loop is formedby a plurality of crawler tracks hinged together, each of whichcomprises a track shoe substrate, hard rubber and a chain track, whereinthe hard rubber is fixed on the track shoe substrate, the chain track isconnected with the track shoe substrate, and adjacent crawler tracks arehinged with each other via the chain track.
 28. The method according toclaim 25, wherein the hard rubber is bonded to the track shoe substrateby epoxy resin and fixed to the track shoe substrate by hex screws. 29.The method according to claim 12, wherein the rolling roof protectionpart comprises a tensioning mechanism, which is configured to push thefirst roller to tension up the closed crawler track loop.